border color transparent code example

Example 1: border color css

border: 1px;
border-color: #3581fc;

Example 2: border color transparent

border-color's transparent property

*** border-color: rgba(111,111,111,0);

rgba(111,111,111,0)
this will invisible your border color.
because that rgba color has property to invisible the border or font of color
if i am correct. other-wise correct my mistake thanks

Example 3: css transparent background color

div {
 opacity:25% ; 
}